Systems and methods for detecting a press on a touch-sensitive surface

ABSTRACT

Systems and methods for displaying and intuitively interacting with keyboards on a touch-sensitive surface are disclosed herein. In one aspect, a method is performed at an electronic device with one or more processors, memory, a touch-sensitive display, and one or more touch sensors coupled to the touch-sensitive display. The method includes: displaying a plurality of keys on a keyboard on the touch-sensitive display and detecting, by the one or more touch sensors, a first contact at a first key of the plurality of keys on the keyboard. The method further includes: determining a value of a signal corresponding to the first contact. When the value is above a first non-zero threshold, the method includes actuating the first key. When the value is between a second non-zero threshold and the first non-zero threshold, the method includes forgoing actuating the first key.

RELATED APPLICATIONS

This application is a continuation-in-part of U.S. patent application Ser. No. 13/308,428, filed Nov. 30, 2011, which is a continuation-in-part of U.S. patent application Ser. No. 13/171,124, filed Jun. 28, 2011, which claims priority to U.S. Provisional Application No. 61/472,799, filed Apr. 7, 2011, U.S. Provisional Application No. 61/418,279, filed Nov. 30, 2010, and U.S. Provisional Application No. 61/359,235, filed Jun. 28, 2010, and is a continuation-in-part of U.S. patent application Ser. No. 12/234,053, filed Sep. 19, 2008, now U.S. Pat. No. 8,325,141, which claims priority to U.S. Provisional Application No. 60/973,691, filed Sep. 19, 2007, each of which is incorporated by reference in its entirety. This application is also a continuation-in-part of U.S. patent application Ser. No. 13/308,416, filed Nov. 30, 2011, which is a continuation-in-part of U.S. patent application Ser. No. 13/171,124, filed Jun. 28, 2011, which claims priority to U.S. Provisional Application No. 61/472,799, filed Apr. 7, 2011, U.S. Provisional Application No. 61/418,279, filed Nov. 30, 2010, and U.S. Provisional Application No. 61/359,235, filed Jun. 28, 2010, and is a continuation-in-part of U.S. patent application Ser. No. 12/234,053, filed Sep. 19, 2008, now U.S. Pat. No. 8,325,141, which claims priority to U.S. Provisional Application No. 60/973,691, filed Sep. 19, 2007, each of which is incorporated by reference in its entirety. This application is also a continuation-in-part of U.S. patent application Ser. No. 13/442,855, filed Apr. 10, 2012, which is a continuation-in-part of U.S. patent application Ser. No. 12/234,053, filed Sep. 19, 2008, now U.S. Pat. No. 8,325,141, which claims priority to U.S. Provisional Application No. 60/973,691, filed Sep. 19, 2007, each of which is incorporated by reference in its entirety.

TECHNICAL FIELD

The present invention relates to a touch-sensitive surface that allows a user to rest their hands or fingers on the touch-sensitive surface without causing an event actuation and, more specifically, the touch-sensitive surface is configured to the user to seamlessly rest, tap, and press on an onscreen keyboard displayed on the touch-sensitive surface.

BACKGROUND

The origin of the modern keyboard as the primary method for inputting text and data from a human to a machine dates back to early typewriters in the 19th century. As computers were developed, it was a natural evolution to adapt the typewriter keyboard to be used as the primary method for inputting text and data. While the implementation of the keys on a typewriter and, subsequently, computer keyboards have evolved from mechanical to electrical and finally to electronic, the size, placement, and mechanical nature of the keys themselves have remained largely unchanged.

As computers evolved and graphical user interfaces developed, the mouse pointer became a common user input device. With the introduction of portable “laptop” computers, various new pointing devices were invented as an alternative to the mouse, such as trackballs, joysticks, and touchpads (also referred to “trackpads”). The overwhelming majority of laptop computers now incorporate the touchpad as the primary pointing device.

Prior to computers, a common office instrument used for performing numerical calculations was the “adding machine.” This device incorporated number keys along with common mathematical operation keys, such as add, subtract, multiply, and divide. The operator performed data entry using these machines, which then displayed the result, printed the result, or both. Experienced adding machine operators were able to memorize the location of the keys and enter data and perform operations very quickly without looking. As computers became common, the need for efficient numeric entry persisted and the “adding machine” functions were added to computer keyboards in the form of a numeric keyboard (or “numpad”) typically located to the right of the standard keyboard.

Combining the three primary user interface devices of keyboard, touchpad, and numpad into a single device results in the device becoming unreasonably large. The problem is further complicated by the fact that many modern keyboards incorporate yet additional keys for page navigation, multimedia controls, gaming, and keyboard settings functions. The result can be a “keyboard” that is often larger than the computer itself.

Further, a new form of portable computing device has recently emerged, commonly referred to as a “tablet” computer. This type of portable computing device typically does not have an integrated keyboard, relying instead solely on touch as the primary means of human-computer interface. Many believe tablets and, eventually, “touch surfaces” that are integrated into daily life will become the standard way humans will interface with “computers” in the future.

While this new paradigm of touch-centric computing has many advantages, one marked disadvantage is the lack of a keyboard. Although external physical keyboards can typically be connected to touch-screen computers, it often defeats the purpose of the device and negates its advantages over traditional laptop computers.

As the evolution of computing devices has progressed toward touch-based user interfaces, a natural evolution for the idea of a keyboard has been to carry it into the virtual world of the computer display by designing onscreen keyboards. Smaller touchscreen devices such as PDAs and Smartphones don't have sufficient screen size to allow people to type on an onscreen keyboard using the conventional method of touch-typing with multiple fingers. As a result, a plethora of inventions have sought to provide alternative text input methods that require less physical space than a conventional keyboard layout. While these inventions have varying benefits for entering text on a small onscreen keyboard, they don't allow text entry at speeds that compare to standard “ten-finger” typing on a conventional keyboard.

Thus, it is desirable to find a yet faster way for entering text that more closely matches the typing style learned on conventional keyboards. In doing so, there are three primary challenges: first, overcoming the relatively large amount of display real estate required for a 10-finger onscreen keyboard. Second, overcoming the lack of tactile feedback common in mechanical keyboards. And third, allowing the user to rest their fingers on the “home-row” position on the onscreen keyboard, as they normally would on a conventional electromechanical keyboard.

Traditionally, these touch sensitive surfaces respond immediately to the user's touch (or release). The paradigm is simple: point, touch, select. While this works well for many applications, it is problematic in situations where the user desires to rest their hands and/or fingers on the surface. A touch-sensitive keyboard (onscreen or stand-alone) is a good example of such a situation; a trained ten-finger touch typist relies on resting their fingers on the home row of the keyboard and then pressing keys to initiate an action. On traditional touch-sensitive surfaces, this isn't possible because as soon as the user touches the surface to rest their fingers, an action is initiated. These solutions don't take into account the need for the user to rest their hands/fingers on the surface.

SUMMARY

Disclosed herein are methods and systems that solve the space problem by integrating the numeric keypad part of the keyboard and the touchpad in the same physical location (e.g., a touch-sensitive surface). This surface can be used to provide all the functions of the keyboard, numpad, and touchpad, but in a much smaller space since it makes it possible to “multiplex” or use the same physical space on the surface for multiple functions. The touch surface may incorporate either a dynamic or static display beneath it, or a mixture of both.

In one aspect, the numeric keypad and the touchpad occupy the same physical space. This is possible due to the fact that the touch-sensitive surface, unlike traditional mechanical keys, can have the spacing, size, orientation, and function of its “keys” dynamically assigned.

In another aspect, the system has three modes of operation: numpad mode, touchpad mode, and auto-detect mode. A visual indicator communicates with the user which mode it is in. The user changes the mode via activation of a key or combination of keys on the keyboard. Visual indicators provide feedback to the user as to which mode the device is in.

In a further aspect, the system automatically determines which mode the user intends based on their interaction with the touch surface. For example, if the user slides their finger across the surface, they most likely intend for it to act as a touchpad, causing the pointer to move. Similarly, if the user taps their finger on a specific sector of the touch surface assigned to a number key, then they most likely intend for it to be used as a numpad.

In some embodiments, the system includes a surface with a multi-mode area, a plurality of touch sensors coupled to the surface, a plurality of motion sensors, and a processor in signal communication with the surface, the plurality of touch sensors, and the plurality of motion sensors is provided. The plurality of touch sensors are configured to generate at least one sense signal based on sense user contact with the surface. The plurality of motion sensors are configured to generate a motion signal based on sensed vibrations of the surface. The processor is configured to determine mode of operation associated with the multi-mode area based on interpretation of at least one of the generated at least one sense signal and the motion signal associated with the multi-mode area.

In some embodiments, the modes of operation include at least two of a keyboard mode, a numeric keypad mode, or a touchpad mode.

In some embodiments, the processor is further configured to determine the mode of operation based on a signal associated with a user selection.

In some embodiments, the surface includes a display device coupled to the processor. In some embodiments, the user selection includes activation of a mode key displayed by the processor on the surface.

In some embodiments, the surface includes at least one visual indicator and the processor illuminates the at least one visual indicator based on the determined mode of operation.

In some embodiments, the processor identifies a default mode of operation. In some embodiments, the processor identifies the default mode of operation to be the touchpad mode after an auto mode selection has occurred followed within a predefined amount of time by a determination of a sliding motion at least on or near the multi-mode area based on the at least one sense signal. In some embodiments, the processor identifies the default mode to be the numeric keypad mode if after the auto mode selection no sliding motion is detected within the predefined amount of time based on the at least one sense signal.

In some embodiments, the processor determines mode of operation to be the touchpad mode, if the processor detects a touch-and-slide motion at the multi-mode area based on the generated at least one sense signal and the motion signal. In some embodiments, the processor determines mode of operation to be at least one of the numeric keypad mode or the keyboard mode, if the processor detects only a tap motion based on the generated motion signals and the detected tap motion did not occur within a threshold amount of time since the detected touch-and-slide motion.

In some embodiments, the processor returns interpretation of the generated at least one sense signal and the motion signal associated with the multi-mode area to the default mode after a predefined period of time has expired since a previously generated at least one sense signal and motion signal associated with the multi-mode area.

In some embodiments, the surface includes a display device coupled to the processor and the processor is configured to generate an image and present the generated image in the multi-mode area of the surface, wherein the generated image is associated with current mode of operation.

In some embodiments, the surface includes a static representation of at least one of a numeric keypad, keyboard or touchpad.

The embodiments disclosed herein also provide systems and methods that allow the user to rest their fingers on the keys of an onscreen keyboard displayed on a touch-sensitive screen and dynamically define the location, orientation, shape, and size of the onscreen keyboard. Rather than the user having to take care to place their fingers on the keys (which typically would require tactile markers on said keys), the system dynamically moves the location of the onscreen keyboard to where the user's fingers are already resting.

In one aspect, the process defines a “home-row definition event,” which is an action performed by the user that causes the system to redefine where the home-row of the onscreen keyboard is located. This location is dynamically established based on the user's action.

In another aspect, the home-row definition event is defined as the user resting all four fingers of both hands simultaneously on the touch-sensitive surface for a preset period of time (e.g., 1 second).

In still another aspect, the home-row definition event is defined as the user double-tapping all four fingers of both hands on the touch-sensitive surface and then resting them on the surface after a second tap.

In yet another aspect, the home-row definition event is defined as the user resting all four fingers of both hands simultaneously on the touch-sensitive surface and then pressing them down momentarily.

These actions (as well as others) are initiated by the user to indicate to the system that the user's fingers are in the home-row resting position. The system then orients the onscreen keyboard accordingly. Note that the keys on the home-row needn't be in a continuous line (as they are on most electromechanical keyboards). Rather, the location of each key on the home-row is defined by the placement of the user's eight fingers during a home-row definition event as sensed by touch sensors, and then extrapolated for keys that are not “home-row resting keys.” In this way the home-row could be along two separate lines, one for each hand placement, or may even form two curves.

Once a home-row definition event has taken place, the system provides feedback to the user in numerous ways. In one aspect, the system provides visual feedback by causing the onscreen keyboard to appear beneath the user's fingers. In another aspect, the system provides an audible cue. In yet another aspect, the system causes the touch-screen to momentarily vibrate.

In one aspect, according to the user's preference, the onscreen keyboard remains visible continuously while typing is taking place. Alternatively, the onscreen keyboard becomes transparent after the home-row definition event. In another aspect, the onscreen keyboard becomes semitransparent, allowing the user to see through the keyboard to content on the screen below.

In yet another aspect, the onscreen keyboard cycles between visible and invisible as the user types. Each time the user taps on the “hidden” onscreen keyboard, the onscreen keyboard temporarily appears and then fades away after a user-settable amount of time.

In yet another aspect, only certain keys become visible after each keystroke. The keys which become temporarily visible are those keys that are most likely to follow the immediately preceding text input sequence (as determined by word and letter databases stored in the system).

In yet another aspect, the onscreen keyboard becomes temporarily visible when the user, with fingers resting in the home-row position, presses down on the surface with their resting fingers.

In still yet another aspect, the onscreen keyboard becomes visible when the user performs a predefined action on the edge of the enclosure outside of the touch sensor area, such as a double- or triple-tap.

In one aspect, the home-row resting keys are defined as the eight keys rested upon by the four fingers of each hand. In yet another aspect, the resting keys may be fewer than eight keys to accommodate users who may not have use of all eight fingers.

In another aspect, the system disambiguates which key was intended according to movement of a particular finger in an intended direction. For example, the user lifts their ring finger and moves it slightly downward and taps. The user may not have moved far enough to reach the virtual location of the adjacent key, but their intention was clearly to select it since they moved from their resting position by a definable threshold distance and tapped in the direction of the adjacent key. Even though the tap may not have occurred on the adjacent key in this example, the system will select it.

In another aspect, the system adjusts the probability of each key being selected, based on the text sequence that immediately preceded it. This probability is used in conjunction with the tap location algorithm described in the previous paragraphs to determine the most likely key the user intended to tap on.

In yet another aspect, the system automatically accounts for “user drift” as they type on the onscreen keyboard. Without the benefit of tactile feel for each key, it is easy for the user to move their hands slightly as they type. The system tracks this behavior by comparing the center of the intended key with the actual location that the user tapped. If a consistent drift is detected over the space of consecutive key events, the system shifts the location of the keys accordingly to accommodate the drift. Again, rather than make the user take care where the keys are, the system moves the keys to where the user's fingers are already located.

If the user drifts too far to the point of straying off of the touch-sensitive area, the system warns them with an audible, visual, and/or vibrating cue.

In another aspect, the method and system monitor for user taps that are on the surface of the portable computing device, but not within the boundaries of the touch sensor. For example, the user may tap an edge of the device's enclosure to indicate a spacebar actuation. As with other tap events, the system correlates the signals from the touch sensors and vibration sensors to determine the tap location. When an absence of signal is detected by the touch sensor, the system recognizes the event as an “external tap” (i.e., a tap on the surface of the device, but outside the boundaries of the touch sensors). External taps generate unique vibration waveforms depending on their location on the enclosure. Characteristics of these waveforms are stored in a database and are used to uniquely identify the general location of the external tap. The external taps, once identified, can be assigned to keyboard functions (such as space or backspace).

In some embodiments, a device including a display, a plurality of touch sensors coupled to the display, a plurality of motion sensors, and a processor in signal communication with the display, the plurality of touch sensors, and the plurality of motion sensors is provided. In some embodiments, the plurality of touch sensors are configured to generate sense signals based on sensed user contact with the display. In some embodiments, the plurality of motion sensors are configured to generate motion signals based on sensed vibrations of a housing. In some embodiments, the processor is configured to generate and present on the display an image of a keyboard having a plurality of keys based on at least one of the generated sense signals or the generated motion signals. In some embodiments, the housing is configured to contain the display, the plurality of touch sensors, the plurality of motion sensors, and the processor.

In some embodiments, the processor is configured to determine location of the keyboard image on the display based on the generated sense signals. In some embodiments, the processor is configured to determine location of the keyboard image on the display based on determination of existence of a home-row definition event. In some embodiments, the processor determines an existence of the home-row definition event when two or more generated sense signals are determined to be active for a predefined amount time.

In some embodiments, the processor is configured to: 1) determine locations of home-row keys of the keyboard image based on determination of location of the generated two or more sense signals; and 2) determine locations of non-home-row keys of the keyboard image based on determined location of at least one of the home-row keys.

In some embodiments, the processor is configured to: 1) determine sizes of home-row keys of the keyboard image based on determination of location of the generated two or more sense signals; and 2) determine sizes of non-home-row keys of the keyboard image based on determined location of at least one of the home-row keys.

In some embodiments, the processor is configured to: 1) determine orientations of home-row keys of the keyboard image based on determination of location of the generated two or more sense signals; and 2) determine orientations of non-home-row keys of the keyboard image based on determined location of at least one of the home-row keys.

In some embodiments, the housing further includes a vibration device configured to generate vibrations at one or more frequencies. In such embodiments, the processor is configured to cause the vibration device to activate at a predefined frequency based on the home-row definition event.

In some embodiments, the housing includes a vibration device configured to generate vibrations at one or more frequencies. In such embodiments, the processor is configured to: 1) place the presented keyboard in a static mode of operation; 2) determine location of at least one user finger based on the sensor signal; and 3) cause the vibration device to create a vibration at a predefined frequency when the determined location of the at least one user finger is within a threshold distance from the at least one home key.

In some embodiments, the vibration device is configured to alter intensity of the vibration based on distance of the at least one user finger from the corresponding home key.

In some embodiments, the housing includes an audio device configured to generate audio signals at one or more frequencies. In such embodiments, the processor is configured to: 1) place the presented keyboard in a static mode of operation; 2) determine location of at least one user finger based on the sensor signal; and 3) cause the audio device to create an audio signal at a predefined frequency when the determined location of the at least one user finger is within a threshold distance from the at least one home key.

In some embodiments, the audio device is configured to alter intensity of the audio signal based on distance of the at least one user finger from the corresponding home key.

In some embodiments, the processor is configured to: 1) periodically receive sense signals associated with continual user finger contact with the display; 2) determine if the received periodic sense signals indicate drift from locations of the sense signals used during the generation and presentation of the keyboard image; and 3) move at least one key of the keyboard image on the display based on a drift indicated of the at least one key.

In some embodiments, the device includes an output device and the processor is configured to: 1) determine if the periodically received sense signals indicate user finger contact drift is within a threshold distance of an edge of the display; and 2) output a signal to the output device if user finger contact drift was determined to be within the threshold distance.

In some embodiments, the processor is configured to: 1) sense a user typing action based on the generated sense signals and the generated motion signals; and 2) change the keyboard image to be at least one of semitransparent or invisible when the user typing action is not sensed for a predefined amount of time.

In some embodiments, after the keyboard image has been made at least one of semitransparent or invisible, the processor is configured to cause the keyboard image to appear at least less transparent when a user typing action has been sensed.

In some embodiments, the processor is configured to: 1) determine at least one next most likely key to be activated based one or more previous key activations; and 2) uniquely display the determined at least one next most likely key.

In some embodiments, the processor is configured to: 1) determine relative movement of one or more user fingers from the home-row keys based on the generated sense signals; and 2) generate a key activation event based on the generated motion signals and the determined relative movement.

In some embodiments, the processor is configured to: 1) generate one or more candidate keys based on at least a portion of the generated sense signals and the generated motion signals; and 2) generate a key activation event by disambiguating the generated one or more candidate keys using a statistical probability model.

In some embodiments, the processor is configured to: 1) determine a size value for at least one key based on statistical probability model and at least one previous key activation event; and 2) alter the keyboard image based on the determined size value for the at least one key.

In some embodiments, the processor is configured to: 1) cause the presented keyboard image to be invisible in an active state based on a sensed first user action; and 2) cause the presented keyboard image to be invisible in an inactive state based on a sensed second user action.

In some embodiments, the generated at least one motion signal is associated with a location relative to the housing. In such embodiments, the processor is configured to identify a function based on the location relative to the housing, when the at least one motion signal has been generated and no sense signals have been generated.

In some embodiments, systems and methods that allow the user to rest their fingers on a touch-sensitive surface and make selections on that surface by pressing are provided. Touch capacitance sensors that typically provide X and Y location data associated with a user's touch are also used to discern finger pressure in the Z direction. This allows the user to make an actuation on the touch screen by simply pressing harder at a location where they may already be resting their finger(s).

In one aspect, the process discerns between the actions of tapping on the surface, resting on the surface, and pressing on the surface. It does so using, in part, thresholds for the touch signal (which may be dynamically altered to accommodate the touch signatures of different users). The process also takes into account the rate of the rising edge of the touch signal to discern between a tap, a resting action, and a press.

It is desirable to allow a human user to rest their hands and/or fingers on a touch surface without causing an actuation, yet still allow other actions issued by the user through touch, such as a press, to be interpreted as commands by the system.

In some embodiments, a system including a touch-sensitive surface and a processor is provided. In some embodiments, the touch-sensitive surface includes a plurality of touch capacitive sensors associated with actionable locations on the surface. In some embodiments, the processor is configured to: 1) determine a user interaction with the touch sensitive surface as a resting action based on one or more signals received from one or more of the plurality of touch sensors, wherein the signals are above a first threshold value; and 2) determine a user interaction with the touch sensitive surface as a press action based on the one or more signals received from one or more of the plurality of touch sensors, wherein the received signals are above a second threshold value.

In some embodiments, the first and second threshold values are predefined. In other embodiments, the first and second threshold values are variable based on individual touch characteristics of each user.

In some embodiments, the processor is configured to assert an activation after a determined resting action for a particular user interaction is followed by a determined press action on an actionable location.

In some embodiments, the processor is further configured to determine a press and hold event when a determined resting action for a particular user interaction is followed by a determined press action that is sustained for longer than a predefined key repeat time.

In some embodiments, the processor is further configured to: 1) determine a user interaction as a selection event based on one of the signals having a leading rising edge with a rate-of-change that exceeds a first rate-of-change threshold followed within a predefined amount of time by the signal decreasing in value at a rate-of-change greater than a second rate-of-change threshold. In some embodiments, the first and second rate thresholds are the same.

In some embodiments, the amplitude of the signal is greater than at least the first threshold value.

In some embodiments, the processor is further configured to: determine the initial user interaction with the touch sensitive surface is the resting action is further determined when a rate-of-change of the leading rising edge of the signal is less than the first rate-of-change threshold and the one or more signals are above the first threshold value.

In some embodiments, the processor is further configured to: determine the initial user interaction with the touch sensitive surface is the press action is further determined when the rate-of-change of the leading rising edge of the signal is less than the first rate-of-change threshold and the one or more signals are above the second threshold value.

In some embodiments, the system includes an output device configured to present a response corresponding to the press action.

In another aspect, a system including a touch-sensitive surface and a processor in signal communication with the touch-sensitive surface is provided. In some embodiments, the touch-sensitive surface includes a plurality of touch capacitive sensors associated with actionable locations on the surface and the sensors are configured to generate one or more signals. In some embodiments, the processor is configured to: 1) determine a user interaction with the touch sensitive surface is a resting action based on one or more signals received from one or more of the plurality of touch sensors, wherein the signals are above a first threshold value; 2) after determination of the resting action, determine a peak of the one or more signals and determine a difference in amplitude of a location of the one or more signals associated with the resting action and the determined peak; 3) if the determined difference is greater than a first predefined delta threshold, determine that a user interaction with the touch sensitive surface is a press action; 4) after determination of the press action, determine that a user interaction with the touch sensitive surface is at least one of: (a) a rest and press release action, if the one or more signals are determined to be at or below the first threshold value; or (b) a press release action, wherein the processor determines an amplitude of a trough of the one or more signals and determines the user interaction is the press release action if the trough amplitude and the determined peak have a difference that is greater than a second predefined delta threshold.

In some embodiments, the first and second predefined delta thresholds are the same.

In some embodiments, the system further includes an output device configured to present a response corresponding to the press action.

In yet another aspect, a system including a touch-sensitive surface and a processor is provided. In some embodiments, the touch-sensitive surface includes a plurality of touch capacitive sensors associated with actionable locations on the surface, the sensors configured to generate one or more signals. In some embodiments, the processor is configured to: 1) determine the initial user interaction with the touch sensitive surface is the resting action is further determined when a rate-of-change of the leading rising edge of the signal is less than the first rate-of-change threshold and the one or more signals are above the first threshold value; 2) determine the initial user interaction with the touch sensitive surface is the press action is further determined when the rate-of-change of the leading rising edge of the signal is less than the first rate-of-change threshold and the one or more signals are above the second threshold value; 3) after determination of the resting action, determine a peak of the one or more signals and determine a difference in amplitude of a location of the one or more signals associated with the resting action and the determined peak; 4) if the determined difference is greater than a first predefined delta threshold, determine that a user interaction with the touch sensitive surface is a press action; 5) after determination of the press action, determine that a user interaction with the touch sensitive surface is at least one of: (a) a rest and press release action, if the one or more signals are determined to be at or below the first threshold value; (b) or a press release action, wherein the processor determines an amplitude of a trough of the one or more signals and determines the user interaction is the press release action if the trough amplitude and the determined peak have a difference that is greater than a second predefined delta threshold.

In some embodiments, the first and second predefined delta thresholds are the same.

In some embodiments, the system further includes an output device configured to present a response corresponding to the press action.

BRIEF DESCRIPTION OF THE DRAWINGS

The implementations disclosed herein are illustrated by way of example, and not by way of limitation, in the figures of the accompanying drawings. Like reference numerals refer to corresponding parts throughout the drawings.

FIG. 1 is a block diagram of an exemplary system formed in accordance with some embodiments.

FIG. 2 is a graphical representation of a state machine, detailing the states of resting and pressing, in accordance with some embodiments.

FIG. 3 is a data flow diagram of exemplary processes performed by the system shown in FIG. 1, in accordance with some embodiments.

FIGS. 4A and B are plots of waveforms representing the touch signal value in the time domain for various press actions, in accordance with some embodiments.

FIG. 5 illustrates the disruption of an electrical field caused by the capacitance of a lightly-touching finger, in accordance with some embodiments.

FIG. 6 illustrates the disruption of an electrical field caused by the capacitance of a finger being pressed strongly into the surface, in accordance with some embodiments.

FIGS. 7A, 7B, and 7C are waveform plots of a tap selection, a rest, and a press action, all in the time domain, in accordance with some embodiments.

FIG. 8 shows an exemplary process performed by the system shown in FIG. 1, in accordance with some embodiments.

FIG. 9A is a schematic of a partial view of an exemplary touch-sensitive surface formed, in accordance with some embodiments.

FIG. 9B is a schematic of a touch-sensitive surface used to illustrate placement of a user's fingers on a keyboard, in accordance with some embodiments.

FIGS. 10A through 1 OF show a flowchart of exemplary processes performed by the system shown in FIG. 1, in accordance with some embodiments.

FIG. 11A is a schematic view of a tablet device with a flat-surfaced virtual keyboard, in accordance with some embodiments.

FIGS. 11B and 11C are schematics of a touch-sensitive surface with onscreen keyboard displays, in accordance with some embodiments.

DETAILED DESCRIPTION

Reference will now be made to embodiments, examples of which are illustrated in the accompanying drawings. In the following description, numerous specific details are set forth in order to provide an understanding of the various described embodiments. However, it will be apparent to one of ordinary skill in the art that the various described embodiments may be practiced without these specific details. In other instances, well-known methods, procedures, components, circuits, and networks have not been described in detail so as not to unnecessarily obscure aspects of the embodiments.

It will also be understood that, although the terms first, second, etc. are, in some instances, used herein to describe various elements, these elements should not be limited by these terms. These terms are used only to distinguish one element from another. For example, a first device could be termed a second device, and, similarly, a second device could be termed a first device, without departing from the scope of the various described embodiments. The first device and the second device are both devices, but they are not the same device.

The terminology used in the description of the various embodiments described herein is for the purpose of describing particular embodiments only and is not intended to be limiting. As used in the description of the various described embodiments and the appended claims, the singular forms “a,” “an,” and “the” are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will also be understood that the term “and/or” as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items. It will be further understood that the terms “includes,” “including,” “comprises,” and/or “comprising,” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof.

As used herein, the term “if” is, optionally, construed to mean “when” or “upon” or “in response to determining” or “in response to detecting” or “in accordance with a determination that,” depending on the context. Similarly, the phrase “if it is determined” or “if [a stated condition or event] is detected” is, optionally, construed to mean “upon determining” or “in response to determining” or “upon detecting [the stated condition or event]” or “in response to detecting [the stated condition or event]” or “in accordance with a determination that [a stated condition or event] is detected,” depending on the context. As used herein, the term “exemplary” is used in the sense of “serving as an example, instance, or illustration” and not in the sense of “representing the best of its kind.”

FIG. 1 shows a block diagram of an exemplary device 100 (comprising human interface hardware components, memory, and processors) for providing a touch interface that, in some embodiments, discerns between tapping, resting, and pressing, provides a multiplexed numeric keypad and touchpad, and/or provides an adaptive onscreen keyboard user interface for alphanumeric input. The device 100 includes one or more touch sensors 120 that provide input to a CPU (processor) 110. The touch sensors 120 notify the processor 110 of contact events when a surface is touched. In one embodiment, the touch sensor(s) 120 (e.g., capacitive touch sensors or a pressure sensor, such as a strain gauge), or the processor 110, include a hardware controller that interprets raw signals produced by the touch sensor(s) 120 and communicates the information to the processor 110, using a known communication protocol via an available data port. In some embodiments, the processor 110 generates an image that is presented on an optional display 130 (touch surface) or alternatively, the display may be static. In some embodiments, the processor 110 communicates with an optional hardware controller to cause the display 130 to present an appropriate image.

In some embodiments, the touch sensors 120 include capacitive touch sensors. In some embodiments, the analog values produced by the capacitive touch sensors are obtained and analyzed (e.g., by processor 110 of device 100). When a user presses their finger against the display 130 (e.g., a display with a touch-sensitive surface or a touchscreen display), more of their finger comes in contact with the surface as the flesh of their fingers flattens against the surface. In some embodiments, this increase in contact causes a corresponding change in the touch capacitive signal (e.g., the analog value produced by the capacitive touch sensors of touch sensors 120). In this way, a press is detected on the touch-sensitive surface.

In some embodiments, the touch sensors 120 include pressure sensors (e.g., a strain gauge) within device 100 or a component thereof (such as an external keyboard). The sensed weight (or pressure) of a contact on a touch-sensitive surface increases as the user presses on a key (e.g., a soft keyboard displayed on display 130). In some implementations, to localize the press, more than one strain gauge is used and the resulting signals detected by each strain gauge are used to determine a location on the touch-sensitive surface corresponding to the press. In some embodiments, the determined location is correlated with additional touch sensor data (e.g., data obtained by capacitive touch sensors included in touch sensors 130) to further refine the location of the press. In some embodiments, the device 100 includes pressure sensors and capacitive touch sensors and device 100 detects occurrence of a press based on output from the pressure sensors and then determines a location on the touch-sensitive surface corresponding to the press using the change in capacitance of the capacitive touch sensors.

In some embodiments, touch sensors 120 include resistive sensors that are used to determine/detect press actions on the touch-sensitive surface. More specifically, as the user touches the touch-sensitive surface, the impedance between two planes on the surface changes and this change is used to detect the different between a rest and a press.

In some embodiments, the device 100 optionally includes one or more vibration sensors 125 (e.g., accelerometers) that communicate signals to the processor 110 when the surface is tapped, in a manner similar to that of the touch sensor(s) 120. The processor 110 generates a keyboard image that is presented on the display 130 (e.g., a display with a touch-sensitive surface) based on the signals received from the sensors (e.g., touch sensors 120 and vibration sensors 125). A speaker 135 is also optionally coupled to the processor 110 so that any appropriate auditory signals are passed on to the user as guidance (e.g., error signals). A vibrator 180 is also optionally coupled to the processor 110 to provide appropriate haptic feedback to the user (e.g., error signals).

In some embodiments, the processor 110 is in data communication with a memory 140, which includes a combination of temporary and/or permanent storage, and both read-only and writable memory (random access memory or RAM), read-only memory (ROM), writable nonvolatile memory, such as FLASH memory, hard drives, floppy disks, and so forth. The memory 140 includes program memory 150 that includes all programs and software such as an operating system 151, press detection software component 152, adaptive onscreen keyboard (“OSK”) software component 154, User Gesture Recognition software 155, and any other application software programs 153. The memory 140 also includes data memory 160 that includes System Settings 161, a record of user options and preferences 162 (e.g., required by the User Gesture Recognition software 155), statistical database(s) 181 (e.g., word database(s)), and any other data 163 required by any element of the device 100.

In some embodiments, the device 100 allows the user to perform at least three interactions on the touch-sensitive surface of display 130 (also referred to as a touchscreen or a touch surface): a touch-and-release selection (or a “tap”), a resting action wherein they rest two or more fingers simultaneously on the touch surface, and a pressing action. Being able to distinguish between these three actions significantly improves the flexibility and usefulness of the user interface of the device 100. For example, the touch surface can be used as a keyboard, allowing the user to rest their fingers on it as they would while touch-typing on a traditional keyboard.

In some embodiments, once a home-row event has been detected by the processor 110 based on signals from the sensors (e.g., touch sensors 120 and vibration sensors 125), the processor 110 positions a virtual onscreen keyboard beneath the user's fingers on the display 130. As the user types, the processor 110 constantly monitors the placement of the user's fingers, as well as tapped locations for each key actuation, and makes adjustments to the location, orientation, and size of each key (and the overall keyboard) to ensure the onscreen keyboard is located where the user is typing. In this way, it is possible to account for the user's “drifting”, or moving their fingers off of the original position of the onscreen keyboard. If the user drifts too far in one direction so-as to reach the edge of the touch sensor area, the processor 110 outputs an audible and/or haptic warning.

At any time, the user may manually re-assign the location of the onscreen keyboard by initiating a home-row definition event (as described above).

In one embodiment, haptic feedback is provided via the vibrator 180 when the user positions their index fingers on the keys commonly-referred to as the “home keys” (F and J keys on a typical English keyboard). In one embodiment, a momentary vibration is issued when the user rests their fingers on the keys using a slightly different frequency of vibration for left and for right. In this manner, the user may choose to move their hands back into a fixed home-row position, when the user chooses to manually re-assign the location of the onscreen keyboard by initiating a home-row definition event (in other words, processor 110 does not dynamically change the position of the onscreen keyboard, the location of the onscreen keyboard instead changes in response to the user's initiation of a home-row definition event). In another embodiment, the intensity of these vibrations may change depending upon finger position relative to the home keys of the fixed home-row.

The device 100 allows the user to type without looking at their fingers or the virtual keyboard. It follows, then, that the keyboard need not be visible at all times. This allows valuable screen space to be used for other purposes.

In one embodiment, the visual appearance of the keyboard varies its state between one or more of the following: visible, partially visible, invisible, and semitransparent. The full keyboard visually appears when a home-row definition event takes place or when the user has rested their fingers without typing for a settable threshold amount of time. As the user begins to type, the keyboard fades away to invisible until the user performs any one of a number of actions including, but not limited to: a home-row definition event, pausing typing, pressing on four fingers simultaneously, or some other uniquely identifying gesture. In another embodiment, the keyboard does not fade away to be completely invisible, but rather becomes semitransparent so the user can still discern where the keys are, but can also see content on the display that is “beneath” the onscreen keyboard.

In one embodiment, the keyboard temporarily “lights”, or makes visible, the tapped key as well as those that immediately surround the tapped key in a semitransparent manner that is proportional to the distance from the tapped key. This illuminates the tapped region of the keyboard for a short period of time.

In one embodiment, the keyboard becomes “partially” visible with the keys having the highest probability of being selected next lighting up in proportion to that probability. As soon as the user taps on a key, other keys that are likely to follow become visible or semi-visible. Keys that are more likely to be selected are more visible, and vice versa. In this way, the keyboard “lights” the way for the user to the most likely next key(s).

In one embodiment, the onscreen keyboard is made temporarily visible by the user performing tap gestures (such as a double- or triple-tap in quick succession) on the outer rim of the enclosure surrounding the touch-sensitive surface.

The various modes of visual representation of the onscreen keyboard may be selected by the user via a preference setting in a user interface program (e.g., by modifying a preference setting stored in user options/preferences 162).

FIG. 2 is a state diagram that illustrates how a press state is determined by the processor 110. The system is initialized in 200 and then enters the idle state 205 where no touch is detected. When a touch signal is detected, the system begins to measure the accumulation of the signal. When the accumulation reaches a pre-defined threshold called the Binary Rest Threshold in 206, the system proceeds to the Plateau State 210. In the Plateau State 210, the user is deemed to be resting their finger(s) on the touch surface. If the user removes their finger(s) from the surface and the Slope Accumulation drops below the Binary Rest Threshold in 211 then the system returns to Idle State 205. From the Plateau State 210 a user may press their finger harder into the surface causing the Slope Accumulation to continue to increase past a pre-defined Positive Press Threshold 212, upon which the system proceeds to the Positive Press Detect State 215 and asserts a press action. As long as the user maintains the pressure while in the Positive Press Detect State 215, the system maintains the press assertion (similar to holding down a key on a traditional keyboard). Once in the Positive Press Detect State 215, the user may lift their finger(s) from the surface causing the Slope Accumulation to decrease below the Binary Rest Threshold in 217 and the system returns once again to the Idle State 205. However, while in the Positive Press Detect State 215, the user may reduce the pressure of the pressing action without completely removing their finger. In this case, a negative inflection point occurs where the touch signal decreases to a point and then either levels out or begins to increase again (i.e. where the slope of the touch signal curve is zero as it passes from negative to positive). When a negative inflection point is detected the system determines if the Slope Accumulation has decreased below a Negative Press Threshold point in 216, at which point the system advances to the Negative Press Detect State 220 and the press action is released. Note that the Negative Press Detect State 220 is similar to the Plateau State 210 in that the user is deemed to be resting. However, the absolute value of the touch signal may be quite different between the two states. When in the Negative Press Detect State 220 the system watches for a maximum inflection point (where the slope of the curve is zero as it passes from positive to negative). When a max inflection point takes place and the Slope Accumulation exceeds the Positive Press Threshold in 221, the system returns to the Positive Press Detect State 215 and asserts a press action. Alternatively, while in the Negative Press Detect State 220, if the Slope signal falls below the Binary Rest Threshold in 222 then the user is deemed to have lifted their finger off the surface and the system returns to the Idle State 205.

FIG. 3 is a data flow diagram that shows how the CPU 110 measures, stores, and analyzes the touch signal. In block 300 the system acquires the raw sensor data from an analog to digital convertor (ADC). The signal is then passed through a low-pass filter in block 305 in order to smooth out any high frequency noise that may be present in the signal. The result is then stored in a Cache (2) in block 310. The slope of the signal is then analyzed in block 315, followed by detection of the minimum and maximum inflection points of the signal in block 320. In block 325 the system accumulates the slope changes and stores the result in Cache (1) in block 330. This calculation determines the amplitude difference between the min and max inflection points. In block 335, the rate of change of the signal is determined and stored in Cache (1) in block 340. The rate of change of the signal is helpful in determining the difference between a tap selection, a resting set-down action, and a press (as illustrated in FIGS. 7A, 7B, and 7C). In block 345 of FIG. 3, the system determines the current press state.

FIGS. 4A and 4B are representations of the touch signal going through a number of conditions resulting in press actions being issued by the system. In FIG. 4A the system follows a very simple process of using fixed threshold values to determine the difference between a resting action and a press. The user touches the surface at 4000 causing the touch signal to rise above the pre-defined Rest Threshold 4050, at which point the signal levels off at 4010 causing an inflection point and putting the system into the Plateau State 210. Sometime later, the user presses harder on the surface causing the touch signal to increase above the Press Threshold 4055 to a local maxima value at 4020 at which point the system asserts a press action (indicated by the black circle). The system continues looking for maxima and minima inflection points. The inflection points found at 4025 and 4030 are ignored since they occur above the Press Threshold, meaning the press asserted at 4020 continues to be asserted. At 4035 the system detects a minima inflection point that falls above the Rest Threshold 4050 and below the Press Threshold 4055 at which point it asserts a press release action (indicated by the hollow circle). The user then presses again causing the touch signal to increase past the Press Threshold. The system detects the maxima inflection point at 4040 and assets another press action. The user then completely lets go, causing the touch signal to fall back to zero. Although no inflection point is detected, at 4045 the system recognizes that the touch signal has fallen below the Rest Threshold 4050 and assets a press release action.

The method described in the above paragraph associated with respect to FIG. 4A is straight-forward, but fails to discern the possible press action that takes place between 4025 and 4030. When a user performs multiple presses in quick succession, the touch signal often remains above the Press Threshold even on the press release action. In order to remedy this short-coming an embodiment is illustrated in FIG. 4B.

Referring to FIG. 4B, the user touches the surface at 4100 causing the touch signal to rise above a pre-defined Rest Threshold 4150, at which point the signal levels off at 4110 causing an inflection point which the system discerns as a Rest assertion and places the state machine into the Plateau State 210. Sometime later, the user presses harder on the surface causing the touch signal to increase to a local maximum value at 4120. The relative change in the signal from 4110 to 4120 is compared with another threshold called the Press Assertion Delta Threshold. If the increase in signal between 4110 and 4120 is greater than the Press Assertion Delta Threshold then a press action is asserted by the system at 4120 (indicated by the solid black circle). Following this assertion, the user decreases the touch pressure between 4120 and 4125 but then once again increases the pressure between 4125 and 4130. At 4125, the system detects a minimum inflection point and measures the change in the touch signal between 4120 and 4125 which is then compared with yet another threshold called the Press Release Delta Threshold. If the absolute value of the decrease in the touch signal between 4120 and 4125 is greater than the Press Release Delta Threshold then a release action is asserted by the system (indicated by the hollow circle). A similar process takes place between 4130, 4135, and 4140 only with different amplitudes and rate of change in the signal. Finally, the user stops pressing at 4140 but keeps their finger in contact with the surface in a resting action at 4145, at which point the system asserts a press release action. After some amount of time, the user then removes their finger from the touch surface and the signal quickly falls to zero. As the signal decreases through the Rest Threshold the system asserts a Rest release action at 4150.

In one embodiment the two methods described in FIG. 4A and FIG. 4B may be selectively combined.

FIG. 5 illustrates one of many possible embodiments in how a touch-sensitive surface can be implemented using capacitance. A touch-sensitive surface 500 is made up of one or more sensors in which an electrode 510 emits an electrical signal forming an electrical field 530, 540, and 570. An adjacent electrode 520 couples with a portion of the formed electrical field 570. The coupled signal at the adjacent electrode 520 is detected and measured by the system. As a human finger 550 touches the surface 500, a portion of the electrical field 540 couples with the finger, resulting in less of the electrical field 570 coupling with the second electrode 520. The processor 110 receives a digital representation of the analog voltage measurement obtained from the second electrode 520 then detects the change of the signal at the second electrode 520 and determines a touch has taken place. The degree to which the electrical field 540 couples with the human finger 550 is dependent, in part, on the amount of surface area 560 with which the finger comes in contact. A “light” touch is shown in FIG. 5 where the finger 550 is just making contact with the touch surface 500. A relatively lower amount of the electrical field 540 is disrupted by the light touch.

FIG. 6 illustrates the effects of a stronger press on the touch capacitance signals. A touch-sensitive surface 600 is made up of one or more sensors in which an electrode 610 emits an electrical signal forming an electrical field 630, 640, and 670. An adjacent electrode 620 couples with a portion of the formed electrical field 670. The coupled signal at the adjacent electrode 620 is detected and measured by the system. As a human finger 650 presses hard on the surface 600, a relatively larger portion of the electrical field 640 couples with the finger, resulting in less of the electrical field 670 coupling with the second electrode 620. The processor 110 receives a digital representation of the analog voltage measurement obtained from the second electrode 620 then detects the change of the signal at the second electrode 620 and determines a press has taken place. The degree to which the electrical field 640 couples with the human finger 650 is dependent, in part, on the amount of surface area 660 with which the finger comes in contact. A “heavy” touch, or press, is shown in FIG. 6 where the finger 650 makes strong contact with the touch surface 600 causing the finger to flatten out at 660. A relatively larger amount of the electrical field 640 is disrupted by the pressing action.

FIGS. 7A, 7B, and 7C illustrate the three actions of a tap selection, a resting set-down action, and a set-down press action respectively. Both the amplitude of the touch signal and the slope of the leading edge of the signal are used to determine which action is being initiated by the user. In FIG. 7A the user quickly taps on a key causing the signal to exceed a pre-defined first threshold indicating a valid touch has taken place. The rising slope of the signal is steep, as is the falling edge, and it peaks between the First Threshold and the Second Threshold (the conditions for a “tap” selection). FIG. 7B illustrates the signal that meets the conditions for a resting set-down action. In this case, the rising edge of the touch signal is relatively slow (as compared to a tap signal) and the amplitude of the signal stabilizes between the First and Second Thresholds. FIG. 7C illustrates the signal that meets the conditions for a set-down press action. In this case, the rising edge of the touch signal is relatively slow as compared to the tap signal, but similar in slope to the rising edge of a rest set-down action. However, the amplitude of the signal continues beyond the Second Threshold indicating the user has pressed harder than a normal touch. The slower rise time, but higher amplitude indicates a set-down pressing action has taken place.

Being able to distinguish between a tap selection, a set-down resting action, and a pressing action is critical in allowing the user to rest their fingers on a touch surface. Further, using the same sensors to detect all three actions has the advantages of keeping the cost of the system relatively lower and simpler.

FIG. 8 shows a flow chart of an exemplary process 800 that allows the same physical area on a touchscreen keyboard to be used to perform the functions of both a numeric keypad and touchpad. The process 800 is not intended to fully detail all the software in its entirety, but is provided as an overview and an enabling disclosure.

The process 800 is provided by the User Gesture Recognition Software 155. At block 805, when the process is first started, various system variables are initialized. For example, event time out (threshold time) is set to zero. At block 810, the process waits to be notified that user contact has occurred within the common area. While the system is waiting in block 810, a counter is incremented with the passage of time. Once user contact has occurred, block 815 determines if the counter has exceeded the maximum time (threshold) allowed for user input (stored as a user option in Data Memory 160).

If the maximum time allowed for user input has been exceeded, then the system resets the mode of the common area to the default mode in block 820. At a decision block 825, the processor 110 determines whether or not the current mode is in touchpad mode. If the current mode is in the touchpad mode, the processor 110 interprets the user contact as a touchpad event and outputs the command accordingly in block 830.

If the current mode is not in the touchpad mode, then the processor 110 assumes the common area is in number pad (numpad) mode and proceeds to decision block 835. In touchpad operation, the user will make an initial touch followed by a sliding motion with their finger (or multiple fingers). In numpad operation, the user will tap on a number key and typically will not slide their finger. The processor 110 uses this difference in typical operation to interpret the user's input in decision block 835 and if a touch-and-slide motion is detected by the processor 110 based on signals provided by the sensors (e.g., touch sensors 120 and vibration sensors 125), the processor 110 changes the current mode to the touchpad mode in block 840, and outputs the user action as a touchpad event in block 845. If the user action is not a touch-and-slide motion then the user action is output by the processor 110 as a numpad event in block 850. After blocks 830, 845, 850, the process 800 returns to block 810.

Note that single taps (or multiple taps in succession) are also common when using a touchpad, and are commonly assigned to functions such as “select” or what is commonly referred to as a “mouse left button” action. These types of actions typically occur shortly after a touch-and-slide motion, and so the system will still be in touchpad mode (since the counter will not yet have reached the threshold in block 815).

Other user gestures on the touchpad are interpreted and assigned to functions, such as multiple finger swipes across the touchpad. While the device 100 is in the touchpad mode, all these gestures are interpreted as touchpad input and sent to the device's operating system as such to be interpreted by whatever system software resides therein. In this way, the system and method acts exactly like any other touchpad when in touchpad mode.

In one embodiment, the default mode is set by the user (typically through control panel software). If the device 100 is at rest with no user input for the user-settable amount of time (threshold), the mode is restored to the default mode.

Gesture Recognition

Auto-detect mode includes, but is not limited to, recognition of the following gestures and their assigned actions:

Gesture Description Action Single-touch slide The user slides one finger Mouse cursor movement across the surface in touchpad mode. Single-touch tap immediately The user taps their finger on Left mouse button click following a single-touch slide the surface within a short period of time after sliding their finger across the surface Single-touch double-tap The user taps their finger twice Left mouse double-click. in quick succession on the surface within a short period of time after sliding their finger across the surface Dual-touch tap immediately The user taps two fingers on Right mouse button click following a single-touch slide the surface within a short (first threshold) period of time after sliding their finger across the surface Single-touch tap The user taps the surface in a Numpad key press single location after not having touched it for a long (second threshold) period of time Single-touch tap following The user taps the surface in a Numpad key press another single-touch tap single location within a short period of time after also tapping a single location Single-touch tap followed by a The user taps the surface in a Left mouse button press and single-touch press single location immediately drag followed by a touch and hold on the surface, then drags their finger across the surface SWYPE Integration

In another embodiment, the touch surface is used in a fourth mode: SWYPE® keyboard. In this mode, the surface represents a keyboard, on which the user may slide their finger from letter to letter, implementing the SWYPE paradigm. This mode is manually selected by the user through some scheme implemented on the keyboard or computer software, or it is selected by functionality provided by the auto-detect mode. In the auto-detect mode, the system observes a sliding motion across the surface and initially interprets it as touchpad movement. However, if the pattern traces out a legitimate word in the fourth mode, the system intelligently switches into the fourth mode and outputs the text. The system stays in the fourth mode for as long as the user is typing. To exit the fourth mode and return to touchpad mode, the user performs a gesture—such as pressing and holding their finger for a few seconds in the same location. Other gestures could also be recognized.

Keyboard Integration

In another aspect of the system, the touch surface is used in a fifth mode: regular keyboard. In the fifth mode, the surface is reconfigured to be a standard QWERTY keyboard. Using patent-pending touch-tap technology, the user can rest their fingers on the touch-sensitive surface and select keys by “tapping” on them. Because this requires more space than any of the other paradigms listed above, it is possible that the device could be used with a diagonal orientation for the fingers. In other words, fingers are displaced along the axis connection opposite corners of the surface. Then, the relative displacement of the fingers from this resting position can be detected to determine which keys were selected (as shown in FIG. 9B). In other words, full sized keys would not be necessary, thus saving space yet allowing comfortable typing.

FIG. 9A shows is a schematic of a keyboard used to illustrate a touch- and tap-sensitive keyboard 900 that incorporates on its forward-facing surface an area 910 incorporating the functions of both a numeric keypad and touchpad. The term “keyboard” in this application refers to any keyboard that is implemented on a touch- and tap-sensitive surface, including a keyboard presented on a touch-sensitive display. The keyboard 900 includes the outline of the area 910 incorporating the functions of the touchpad, the keys assigned to the numeric keypad, as well as the selection keys commonly referred to as the “left and right mouse buttons” 930. “Mode” refers to the type of function that is assigned to the commonly-shared area 910. A separate mode key 920 allows the user to manually select between Touchpad mode, numeric keypad (or “numpad”) mode, or “Auto” mode (whereby the function assigned to common area 910 is determined by the system according to the actions of the user on the surface of the common area 910).

In one embodiment, the system displays the current mode (touchpad or number pad) with visual indicators 920 along with an “Auto” mode visual indicator. In this way, the user can know which mode the system is in at all times. In one embodiment, a mode key 924 is provided below the indicators 920 on the keyboard. User activation of the mode key 924 causes the processor 110 to switch to another mode.

In one embodiment, the user may define the default mode to be the touchpad mode by first selecting Auto mode with the mode key 924 immediately followed by a touch-and-slide motion on the common area 910. In the absence of a touch-and-slide motion immediately following the selection of Auto mode, the processor 110 will set the default mode to numpad mode.

In another embodiment, the touch surface is used in a fourth mode: keyboard. In the fourth mode, the surface represents a keyboard, on which the user may enter text using a plethora of methods designed for smaller touch surfaces (such as those invented for smartphones). This mode is manually selected by the user through some scheme implemented on the keyboard or computer software, or it is selected by functionality provided by the auto-detect mode. The device stays in keyboard mode for as long as the user is typing. To exit the keyboard mode and return to the touchpad mode, the user performs a predefined gesture—such as pressing and holding all their fingers for a few seconds in the same location. The processor recognizes the unique gesture, then changes mode accordingly. Other gestures could also be recognized.

In another embodiment, the touch surface incorporates a dynamic display. The display changes in accordance with the current mode setting to display the appropriate image in the common area. For example, when numpad mode is selected, a numeric keypad is displayed; when touchpad is selected, a blank rounded rectangle is displayed; and so on.

FIGS. 10A-10F show an exemplary process performed by the device 100. The flowcharts shown in FIGS. 10A-10F are not intended to fully detail the software in its entirety, but are used for illustrative purposes.

FIG. 10A shows a process 1000 executed by the processor 110 based on instructions provided by the OSK software component 154. At block 1006, when the process 1000 is first started, various system variables are initialized, such as minimum rest time, number of finger touch threshold, drift distance threshold, and key threshold. At block 1008, the process 1000 waits to be notified that a contact has occurred within the area of a touch-screen. Then, at block 1010, home-row detection occurs based on signals from one or more of the sensors (e.g., touch sensors 120 and vibration sensors 125). Home-row detection is described in more detail in FIG. 10B. At a block 1012, locations of keys for the to-be-displayed virtual keyboard are determined based on the sensor signals. The key location determination is described in more detail in FIG. 10C. Next, at block 1016, key activations are processed (see FIGS. 10D and 10E for more detail.) At a block 1018, user's finger drift is detected based on the sensor signals. Finger drift is described in more detail in FIG. 10F. Then, at block 1020, a virtual keyboard is presented on the display 130 based on at least one of the determinations made at blocks 1010-1018. The process 1000 repeats when a user removes their eight fingers and then makes contact with the touchscreen.

FIG. 10B shows the home-row detection process 1010. At a decision block 1034, the process 1010 determines if a user has rested their fingers on the touch-screen for a minimum amount of time (i.e., minimum rest threshold). At a decision block 1036, the process 1010 determines if the appropriate number of fingers have rested on the touch surface, thus initiating a home-row definition event. If the conditions in either of blocks 1034 or 1036 are not met, the process 1010 exits without changing the location of the onscreen keyboard.

Once both the time and number of resting fingers requirements are met, the processor 110 determines the location of the resting fingers, see block 1040. A KeySpaceIndex (or “KSI”) value is then determined in block 1042. The KSI is used to customize the onscreen keyboard to the size and spacing of the user's fingers.

The KSI may change from one home-row definition event to the next, even for the same user. In one embodiment, all four fingers of each hand are resting on the touch surface to initiate the home-row definition event. In such a case, the KSI is given by the following formula: KSI=(Average RestingKey Spacing)/(Modeled Nominal Spacing)=[(a+b+c)/3]/A=(a+b+c)/3A

where,

-   -   A=a modeled nominal distance between keys (typically 19 mm)     -   a=the measured distance between RestingKey1 and RestingKey2     -   b=distance between RestingKey2 and RestingKey3     -   c=distance between RestingKey3 and RestingKey4.

The KSI formula can be adjusted accordingly if fewer than four resting fingers are used to initiate a home-row definition event (as defined in a set of user preferences stored in a database). The KSI is used in subsequent processes.

A data model for a standard onscreen keyboard is stored in memory of the system. In this data model, the onscreen keyboard layout is divided into two sections: keys normally typed with the right hand, and keys normally typed with the left hand. Further, each key is related to the home-row resting key that is rested upon by the finger that is most likely to type that particular key (defined as the “related resting key”). The location of each key is defined in the data model as a relative measurement from its related resting key.

An exemplary formula for determining the location of each key is given as: Key(x′,y′)=KeyModel(x*KSI,y*KSI)

Where,

-   -   x=the nominal stored x distance from the center of the Related         Resting Key (RRK)     -   y=the nominal stored y distance from the center of the RRK

It is possible that the modified key positions of two or more keys may overlap. If that is the case, the size of the overlapping keys is reduced until the overlap is eliminated.

The orientation of the X-Y axis is determined separately for each resting key. For each of the left and right sectors, a curve is fit to the resting keys in that sector. The X-Y axis for each key is then oriented to be the tangent (for the x-axis) and orthogonal-tangent (for the y-axis) to the curve at the center of that key.

FIG. 10C shows the assigning key locations process 1012. The process 1012 is repeated for each key of the keyboard. At block 1052, a pre-stored location for each key is retrieved from the database 181, relative to its associated resting key position in the form [RestingKey, Ax, Ay]. For example, the key representing the letter “R” is associated with the resting key L1 (typically the letter “F”), and is positioned up and to the left of L1. Thus, its data set would be [L1, −5, 19] (as measured in millimeters). Similar data is retrieved for each key from the database 181. At block 1054, a new relative offset is calculated for each key by multiplying the offset retrieved from the database by the KSI. At block 1058, the absolute coordinates of each key is then determined by adding the new offset to the absolute location of the associated resting key as determined at block 1054. At decision block 1060, the process 1012 tests to see if any keys are overlapping, and if so, their size and location are adjusted at block 1062 to eliminate any overlap. Then the process 1012 returns to the process 1000.

FIG. 10D shows the process-key actuations process 1016, whereby the actual key events are determined and output. The process 1016 begins at decision block 1070 that tests if a valid touch-tap event has occurred. This is determined through a correlation between the touch sensor(s) 120 and vibration sensor(s) 125. Candidate keys are scored by applying a key scoring algorithm at block 1072. The key with the highest score is then output at block 1074 and the process 1016 returns.

FIG. 10E shows a process for the key scoring algorithm from block 1072 of FIG. 10D. At block 1080, signals received by the touch sensors 120 and the vibration sensors 125 are correlated to determine where the user's tap took place and to define keys in the immediate vicinity as “candidate keys”. By considering keys surrounding the area of the tap (rather than just the key where the tap took place), the processor 110 accounts for ambiguity in the user's typing style. At a decision block 1082, the process 1072 tests to see if the user moved their finger from a resting key to type. Note that in typical typing styles, even a 10-finger touch typist will not constantly rest all four fingers at all times. So, it isn't a prerequisite that a change in a resting key take place in order for a valid key to be typed on. However, if a change does take place to the state of a resting key in the vicinity of the candidate keys (or if it is a candidate key itself), useful information can be obtained from such change as explained at block 1084. At block 1084 a virtual line is calculated between the resting key in the vicinity of the tap for which a state change was detected, and the location of the tap, as calculated at block 1080. The virtual line extends beyond the tap location. At block 1084 keys that the projected line passes through or by are determined and the processor 110 increases the score of those keys accordingly. In this way, relative movements in the direction of the desired key are correlated to that key, even if the tap location doesn't occur directly on the key. At block 1088, the processor 110 takes into account the preceding words and characters that were typed as compared with linguistic data stored in data memory 181 (e.g., statistical databases 181). This includes commonly known disambiguation methods such as: letter-pair statistical frequencies, partial-match prediction, inter-word prediction, and intra-word prediction. Appropriate scoring is assigned to each candidate key. At block 1090, the candidate key with the highest score representing the highest calculated probability of the user's intended selection is determined and the process 1072 returns.

FIG. 10F shows the drift detection process 1018 for accommodating when the user inadvertently moves their hands (or “drifting”) as they type. The process 1018, at block 1091, compares the actual tap location with the current center of the displayed intended key, and stores the difference in the X and Y coordinates ΔX and ΔY. These differences are added to a previous cumulative total from previous keystrokes at block 1092. At decision block 1093, the processor 110 tests if the cumulative difference in either direction exceeds a pre-stored variable called “DriftThreshold” (as defined from user preference or default data stored in data memory 162 (e.g., user options/preferences 162)). If the threshold is exceeded, the processor 110 moves the location of the entire keyboard in block 1094 by the average of all ΔXs and all ΔYs since the last location definition event. If the cumulative differences do not exceed the DriftThreshold for the entire keyboard, then a similar calculation for the individual selected key is performed at block 1097. At decision block 1098, the processor 110 tests if the cumulative differences for that individual key exceeds the user-defined key threshold after block 1097 and, if so, adjusts its location at block 1099. The key threshold is the permissible amount of error in the location of the tap as compared to the current location of the associated key. When key threshold has been exceeded, the associated key will be moved. After block 1094, if the decision at block 1098 is No, or after block 1099, then at block 1095, the processor 110 tests if any of the new positions overlap with any other keys and if the overall keyboard is still within the boundaries of the touch sensors. If there are any conflicts for either test, they are corrected with a “best fit” algorithm in block 1096 and then exits. Also, if no conflicts are found, the process 1018 returns.

Even though the method will allow the user to type without the onscreen keyboard being visible, there are still times when a user will want to view the keys. For example, if they don't know which key is associated with a desired character, or where certain characters are located on a separate numeric and/or symbols layer. Other users may not be able to type from rote, knowing by memory where each character is located. For these, and other reasons, it is important to visually present the onscreen keyboard on the screen of the device.

According to stored user's preference, the onscreen keyboard can remain visible continuously while typing is taking place. Alternatively, the onscreen keyboard becomes transparent after the home-row definition event. In one embodiment, the onscreen keyboard becomes semitransparent so-as to allow the user to see through the keyboard to content on the screen below.

In the case where the keyboard is set to be invisible, other content may be displayed on the full screen. There may be other user interface elements, such as buttons, that will appear to be active yet be located below the invisible onscreen keyboard. In such a case, the device 100 intercepts the user's input directed toward such an element and causes the onscreen keyboard to become visible, reminding the user that it is indeed present. The user may then elect to “put away” the keyboard by pressing a corresponding key on the keyboard. Note that putting away the keyboard is not the same as making it invisible. Putting away the keyboard means to “minimize” it off the screen altogether, as is a common practice on touchscreen devices.

In one embodiment, the onscreen keyboard cycles between visible and invisible as the user types. Each time the user taps on the “hidden” onscreen keyboard, the onscreen keyboard temporarily appears and then fades away after a user-settable amount of time.

In one embodiment, only certain keys become visible after each keystroke. The keys that become temporarily visible are those keys that are most likely to follow the immediately preceding text input sequence (as determined based on word and letter databases stored in the system).

In one embodiment, the onscreen keyboard becomes temporarily visible when the user, with fingers resting in the home-row position, presses down on the surface with their resting fingers based on changes sensed by the touch sensors 120.

In one embodiment, the onscreen keyboard becomes visible when the user performs a predefined action on the edge of the enclosure outside of the touch sensor area, such as a double- or triple-tap.

The onscreen keyboard, if set to appear, will typically do so when a text-insertion condition exists (as indicated by the operating system 151), commonly represented visually by an insertion carat (or similar indicator).

In one embodiment, the tactile markers commonly used on the F and J home-row keys are simulated by providing haptic feedback (such as a vibration induced on the touchscreen) when the user positions their fingers to rest on those keys. In this way, the user may choose for the keyboard to remain stationary in the same onscreen position, yet find the correct placement of their hands by touch only (without looking).

To increase the accuracy of the keyboard, statistical models of language are used. If a touch/tap event yields an ambiguous key choice, the statistical models are called upon by the processor 110 to offer the key that is most likely what the user intended.

This “disambiguation” is different from other methods used for other text input systems because a permanent decision about the desired key must be made on the fly. There is no end-of-word delineation from which word choices can be displayed to the user and the output modified. Instead, each time the user taps on a key, a decision must be made and a key actuation must be sent to a target application program (i.e., text entry program).

Several statistical analysis methods can be employed: partial-match letter prediction, current-word prediction, next-word prediction, and conjunctive next-word prediction. These are explained in detail in the following sections.

Prediction by Partial Match

A well-known algorithm originally invented for data compression useful in this case is prediction by partial match (or PPM). Applied to a keyboard, the PPM algorithm is used to predict the most likely next character, given a string of characters that has already occurred (of length k). Computing time and resources grow exponential with the value of k. Therefore, it is best to use the lowest value of k that still yields acceptable disambiguation results.

By way of example, let k=2. A process looks back at the past two characters that have been entered and then compare probabilities from a database of the most likely next character(s) to be typed. For example, the underlined letters below show what is used to predict the next most likely letter:

An

An

An e

An ex

An exa

An exam

An examp

An exampl

An example

The data storage required for this algorithm for a total number of possible keys A is: _(A) ^(k+1)

For a typical onscreen keyboard, this process consumes less than 1 MB of data.

The statistical model is built up for each language (although with a small value for k); the table may be similar for languages with common roots. The model also dynamically updates as the user enters text. In this way, the system learns the users typing patterns and more accurately predicts them as time goes on.

Language variants are provided in the form of language-specific dictionaries configured through an operating system control panel. The control panel identifies the current user's language from the system locale and selects the appropriate prediction dictionary. The dictionary is queried using a continuously running “systray” application that also provides new word identification and common word usage scoring.

In one embodiment, a database made up of commonly used words in a language is used to disambiguate intended key actuations. The algorithm simply compares the letters typed thus far with a word database, and then predicts the most likely next letter based on matches in the database.

For example, say the user has typed “Hel.” Possible matches in the word database are:

Hello (50)

Help (20)

Hell (15)

Helicopter (10)

Hellacious (5)

The numbers beside each word represent their “frequency” of use, normalized to 100. (For convenience sake, the total frequencies in this example add up to 100, but that would not normally be the case).

The candidate letters that most likely follow “Hel” are:

L (70)—probabilities added for the words “Hello”, “Hell”, and “Hellacious”

P (20)

I (20)

This example is particularly useful, in that the letters L, P, and I are all in close proximity to one another. It is possible, and even likely, that the user may tap on a location that is ambiguously near several keys (I, 0, P, or L, for example). By adding word prediction, the choice is significantly disambiguated; in this example, the obvious most-likely next letter is “L.”

Note that this implementation of the word prediction algorithm is different from that traditionally used for onscreen keyboards, because it is not truly a word prediction system at all: it is a letter prediction system that uses a word database.

In one embodiment, word pairs are used to further disambiguate the most likely selected key. With simple word prediction, there is no context to disambiguate the first letter of the current word; it is completely ambiguous. (This disambiguation is reduced slightly for the second letter of the word, and so on for the remainder of the word.) The ambiguous nature of the first few letters of a word can be significantly reduced by taking into account the word that was entered immediately previous to the current word; this is called “next-word prediction”.

For example, if the word just typed was “Cleankeys”, common next words stored in the database may be:

Keyboard (80)

Inc. (20)

Is (20)

Will (15)

Makes (10)

Touch (5)

If the user ambiguously taps between the I key and the K key for the start of the next word, the next-word prediction algorithm can help disambiguate (in this case, “K” would win).

Logic may dictate that the concept of considering the previous word typed could be carried to the previous k words typed. For example, for k=2, the system could store a database that has 2nd-degree next-words (or next-next-words) for every word in the database. In other words, look back at the two previous words in combination to determine the most likely word to follow. However, this quickly becomes unwieldy, both in terms of space and computing power. It simply isn't practical to store that many combinations, nor is it very useful, because most of those combinations would never occur.

There is, however, a significant exception that is worth considering: words that have a very large number of next-word candidates. Such is the case for parts of speech known as conjunctions and articles.

The seven most-used conjunctions in the English language are: and, but, or, for, yet, so, nor.

The articles in the English language are: the, a, an.

By special-casing these 10 words, the system improves first-letter predictions.

Consider the phrase: kick the _(—.)

Because every noun in the database is most likely a next-word candidate for the article “the”, there is very little use derived from the next-word prediction algorithm. However, if the context of “kick” before the article “the” is retained, a much richer next-next-word choice is attained. Effectively, a new “word” is stored in the database called “kick the.” This new entity has the following next-word candidates:

Ball (50)

Bucket (20)

Habit (15)

Can (10)

Tires (5)

Thus one can confidently predict that the most likely next letter to follow the phrase “kick the” is the letter “B.”

Any word that is found combined with a conjunction or article is combined with those parts of speech to form a new word entity.

A notable difference between the letter-by-letter prediction system described herein and a word-based prediction system is the ability to dynamically reorient the prediction for each letter. For example, if a guess is wrong for a specific key and the desired word subsequently becomes clear, the algorithm abandons the choice it made for the incorrect letter and applies predictions for the remaining letters, based on the newly determined target word.

For example:

Ambiguous Text Entered Candidate Keys Predicted Words Predicted Letter Kick the B, h, g Ball, bucket, habit, B goat, garage Kick the b A, q, s Ball, habit, wage A Kick the ba B, v, space habit B Kick the bab I, k, o habit I Kick the babi T, r habit T Kick the babit Space, n, m habit space

As the word progresses, it is shown that the initial letter “B” should have been an “H” (these letters are near one another on the qwerty keyboard layout and one could easily be mistaken for the other). But rather than commit completely to that first letter, and only consider words that start with “B,” other candidates are still considered by the system in predicting the second letter. So, B, H, and G are considered as the first letter for subsequent keys. In this way, the mistake isn't propagated and the user would need to only make one correction instead of potentially many.

So, for each new key entered, keys that are adjacent to the new key, as well as other ambiguous candidates, are considered as possibilities in determining subsequent letters.

When a mistake is made and the user backspaces and corrects it, the system can feed that data back into the algorithm and make adjustments accordingly.

For example, the user ambiguously enters a key in the middle of the keyboard and the scoring algorithm indicates that potential candidates are “H,” “J,” and “N”; the scores for those three letter fall into the acceptable range and the best score is taken. In this example, let's say the algorithm returns the letter “J” as the most likely candidate and so that is what the keyboard outputs. Immediately following this, the user unambiguously types a <backspace> and then an “H,” thus correcting the error.

This information is fed back into the scoring algorithm, which looks at which sub-algorithms scored an “H” higher than “J” when the ambiguous key was originally entered. The weighting for those algorithms is increased so if the same ambiguous input were to happen again, the letter “H” would be chosen. In this way, a feedback loop is provided based directly on user corrections.

Of course, the user can make typing mistakes themselves that are not the result of the algorithm; it correctly output what the user typed. So, care must be taken when determining if the user correction feedback loop should be initiated. It typically occurs only when the key in question was ambiguous.

A user-settable option could allow the keyboard to issue backspaces and new letters to correct a word that was obviously wrong. In the example above, once the predictor determines that the only logical word choice is “habit,” the keyboard would issue backspaces, change the “b” to an “h,” reissue the subsequent letters (and possibly even complete the word).

With so many factors lending to the disambiguation of a key, all algorithms can potentially add to the candidacy of a key. This approach is called scoring; all algorithms are weighted and then added together. The weighting is dynamically changed, to tune the scoring algorithm to the user's typing style and environment.

FIG. 11A shows a schematic view representative of a typical handheld tablet computer 1150 that incorporates on its forward-facing surface a touch-sensitive display 1152 and a keyboard 1154 designed and used in accordance with an embodiment. The keyboard 1154, when used in accordance with some embodiments, generates text that is output to the text display region 1158 at a text insertion location 1160. The term “keyboard” in this application refers to any keyboard that is implemented on a touch-and tap-sensitive surface, including a keyboard presented on a touch-sensitive display. The keyboard 1154 shows the letters of the alphabet of the respective language selected by the user on individual keys, arranged in approximately the standard “QWERTY” arrangement found on most keyboards.

In one embodiment, the orientation, location, and size of the keyboard (as well as individual keys) are adaptively changed according to the input behavior of the user. When the user rests their fingers on the touch surface 1152 in a certain way, the system moves the keyboard 1154 to the location determined by the resting fingers. When the user intends to actuate a key on the keyboard 1154, they “tap” on the desired key by lifting their finger and striking the surface 1152 with discernible force. User taps that occur on areas 1162, 1164 outside of the touch sensor area 1152 are detected by the vibration sensor(s) and may also be assigned to keyboard functions, such as the space bar.

The absence of a touch sensor signal is in effect, a signal with a value of zero, and when correlated with a tap (or vibration) sensor can be used to uniquely identify a tap location. In one embodiment, the vibration signal for specific regions outside of the touch sensor area 1152, such as those indicated at areas 1162, 1164, are unique and stored in a database by the system. When the absence of a touch signal occurs in conjunction with a tap event, the system compares the vibration characteristics of the tap with those stored in the database to determine the location of the external tap. In one embodiment, the lower outer boundary area 1162 is assigned to a space function, while the right outer boundary area 1164 is assigned to a backspace function.

FIG. 11B is a schematic view representative of an exemplary virtual onscreen keyboard 1170. The keyboard 1170 is divided into two halves: a left half 1172 and a right half 1174 (as correlates to the left and right hands of the user). The two separate halves 1172, 1174 are not aligned with each other. The eight keys 1178 that are typically rested on by the user are labeled in bold according to which finger is typically used for that key (e.g., L1 represents the index finger of the left hand, L4 represents the little finger of the left hand, and so on). All other non-home-row keys are indicated by a label showing which finger is normally used to type that key using conventional touch-typing techniques. It should be noted, however, that there are many typing styles that do not use the finger placements as shown in FIG. 11B, and those labels are included herein for illustrative purposes only.

The left half of the keyboard 1172 shows all the keys aligned in horizontal rows, as they would be on a traditional electromechanical keyboard. In one embodiment as shown on the right half 1174, the home-row keys are dispersed along an arc to better fit the normal resting position of the user's four fingers. Non-home-row keys are similarly dispersed in accordance with their relative location to the home-row resting keys. Further, in one embodiment, the size of each key may also vary in accordance with the statistical likelihood that the user will select that key (the higher the likelihood, the larger the key).

FIG. 11C is a schematic view representative of the virtual onscreen keyboard 1184 that is oriented at an angle in accordance with an embodiment. The user may rest their hands 1190 on the touch-sensitive surface 1192 of a typical handheld tablet computer 1194 at any location and orientation that they wish. In this case, the hands are spread apart further than normal and oriented at an angle as referenced to the straight edges of the device 1194. The user initiates an action indicating a “home-row definition event,” which, may include, but is not limited to, the following: resting all eight fingers for a short, user-definable period of time; double-tapping all eight fingers simultaneously on the surface 1192 and then resting them on the surface 1192; or pressing down all eight fingers simultaneously as they are resting on the surface 1192. In another embodiment, not all eight fingers are required to initiate a home-row definition event. For example, if someone was missing their middle finger, a home-row definition event may be initiated by only three fingers on that hand. Here the user has rested their hands 1190 at an angle on the tablet computer 1194, thus causing a processor of the computer 1194 to generate and display the virtual onscreen keyboard 1184 at an angle.

Although some of various drawings illustrate a number of logical stages in a particular order, stages which are not order dependent may be reordered and other stages may be combined or broken out. Furthermore, in some embodiments, some stages may be performed in parallel and/or simultaneously with other stages (e.g., operations 315, 320, and 325 in FIG. 3 may all be performed together or substantially in parallel). While some reordering or other groupings are specifically mentioned, others will be apparent to those of ordinary skill in the art, so the ordering and groupings presented herein are not an exhaustive list of alternatives. Moreover, it should be recognized that the stages could be implemented in hardware, firmware, software, or any combination thereof.

The foregoing description, for purpose of explanation, has been described with reference to specific embodiments. However, the illustrative discussions above are not intended to be exhaustive or to limit the embodiments to the precise forms disclosed. Many modifications and variations are possible in view of the above teachings. The embodiments were chosen and described in order to best explain the principles and their practical applications, to thereby enable others skilled in the art to best utilize the embodiments and various embodiments with various modifications as are suited to the particular use contemplated. 

What is claimed is:
 1. An electronic device, comprising: a touch-sensitive display; one or more processors; memory storing one or more programs, wherein the one or more programs are configured to be executed by the one or more processors, the one or more programs including instructions for: displaying a keyboard, on the touch-sensitive display, wherein the keyboard includes a plurality of different symbols displayed on respective individual keys; detecting a touch input at the touch-sensitive display while the touch-sensitive display is operated in a keyboard mode; in response to detecting the touch input at the touch-sensitive display, determining whether the touch input corresponds to typing at the displayed keyboard; upon determining that the touch input corresponds to typing: interpreting the touch input as a keyboard event; and activating one or more keys on the keyboard on the touch-sensitive display based on a location of the touch input; detecting, via the touch-sensitive display, a predefined mode-changing gesture over the displayed keyboard; and in response to detecting the predefined mode-changing gesture over the displayed keyboard: ceasing to display the keyboard on the touch-sensitive display; and operating the touch-sensitive display in a touchpad mode that interprets gestures on the touch-sensitive display as touchpad inputs.
 2. The electronic device of claim 1, wherein: ceasing to display the keyboard on the touch-sensitive display includes: ceasing to display a plurality of symbols on respective individual keys of the keyboard on the touch-sensitive display, and displaying, on the touch-sensitive display, a representation of a touchpad.
 3. The electronic device of claim 1, wherein detecting the predefined mode-changing gesture includes detecting a user pressing and holding a predefined number of contacts for a predefined amount of time on the touch-sensitive display.
 4. The electronic device of claim 1, wherein detecting the predefined mode-changing gesture includes detecting that a user has stopped providing typing inputs at the displayed keyboard for at least a predefined amount of time.
 5. The electronic device of claim 1, wherein detecting the predefined mode-changing gesture includes detecting, via a vibration sensor of the electronic device, a tap outside of the touch-sensitive display.
 6. The electronic device of claim 1, wherein activating one or more keys on the keyboard on the touch-sensitive display based on a location of the touch input includes determining relative displacement of the touch input relative to a resting position and determining appropriate one or more keys to activate based on the relative displacement.
 7. The electronic device of claim 1, wherein the one or more programs further comprise instructions for, after interpreting an additional touch input on the touch-sensitive display as a first touchpad event while the touch-sensitive display is operating in the touchpad mode, moving a cursor on the touch-sensitive display in accordance with the additional touch input.
 8. The electronic device of claim 7, wherein the one or more programs further comprise instructions for, after interpreting the additional touch input as the first touchpad event, detecting a tap on the touch-sensitive display immediately followed by a dragging motion across the touch-sensitive display and, in response, interpreting the dragging motion as a second touchpad event, wherein the second touchpad event corresponds to dragging a currently-displayed object across the touch-sensitive display.
 9. The electronic device of claim 1, wherein the one or more programs further include instructions for: in response to detecting a sliding motion across the touch-sensitive display while it is operating in the touchpad mode, interpreting the sliding motion as a touchpad event, where the sliding motion is distinct from the predefined mode-changing gesture.
 10. The electronic device of claim 9, wherein the one or more programs further comprise instructions for, after interpreting the sliding motion as a touchpad event, determining whether a path followed by the sliding motion on the touch-sensitive display traces out a word and, in accordance with a determination that the path followed by the sliding motion traces out the word, outputting text on the touch-sensitive display corresponding to the word.
 11. A method, comprising: at an electronic device with one or more processors, memory, and a touch-sensitive display: displaying a keyboard on the touch-sensitive display, wherein the keyboard includes a plurality of different symbols displayed on respective individual keys; detecting a touch input at the touch-sensitive display while the touch-sensitive display is operated in a keyboard mode; in response to detecting the touch input at the touch-sensitive display, determining whether the touch input corresponds to typing at the displayed keyboard; upon determining that the touch input corresponds to typing: interpreting the touch input as a keyboard event; and activating one or more keys on the keyboard on the touch-sensitive display based on a location of the touch input; detecting, via the touch-sensitive display, a predefined mode-changing gesture over the displayed keyboard; and in response to detecting the predefined mode-changing gesture over the displayed keyboard: ceasing to display the keyboard on the touch-sensitive display; and operating the touch-sensitive display in a touchpad mode that interprets gestures on the touch-sensitive display as touchpad inputs.
 12. The method of claim 11, wherein ceasing to display the keyboard on the touch-sensitive display includes: ceasing to display a plurality of symbols on respective individual keys of the keyboard on the touch-sensitive, display, and displaying, on the touch-sensitive display, a representation of a touchpad.
 13. The method of claim 11, wherein detecting the predefined mode-changing gesture includes detecting a user pressing and holding a predefined number of contacts for a predefined amount of time on the touch-sensitive display.
 14. The method of claim 11, wherein detecting the predefined mode-changing gesture includes detecting that a user has stopped providing typing inputs at the displayed keyboard for at least a predefined amount of time.
 15. The method of claim 11, wherein detecting the predefined mode-changing gesture includes detecting, via a vibration sensor of the electronic device, a tap outside of the touch-sensitive display.
 16. The method of claim 11, wherein activating one or more keys on the keyboard on the touch-sensitive display based on a location of the touch input includes determining relative displacement of the touch input relative to a resting position and determining appropriate one or more keys to activate based on the relative displacement.
 17. The method of claim 11, further comprising, after interpreting an additional touch input on the touch-sensitive display as a first touchpad event while the touch-sensitive display is operating in the touchpad mode, moving a cursor on the touch-sensitive display in accordance with the additional touch input.
 18. The method of claim 17, further comprising, after interpreting the additional touch input as the first touchpad event, detecting a tap on the touch-sensitive display immediately followed by a dragging motion across the touch-sensitive display and, in response, interpreting the sliding motion as a second touchpad event, wherein the second touchpad event corresponds to dragging a currently-displayed object across the touch-sensitive display.
 19. The method of claim 11, further comprising: in response to detecting a sliding motion across the touch-sensitive display while it is operating in the touchpad mode, interpreting the sliding motion as a touchpad event, where the sliding motion is distinct from the predefined mode-changing gesture.
 20. The method of claim 19, further comprising, after interpreting the sliding motion as a touchpad event, determining whether a path followed by the sliding motion on the touch-sensitive display traces out a word and, in accordance with a determination that the path followed by the sliding motion traces out the word, outputting text on the touch-sensitive display corresponding to the word.
 21. A non-transitory computer-readable storage medium storing executable instructions that, when executed by one or more processors of an electronic device with a touch-sensitive display, cause the electronic device to: display a keyboard, on the touch-sensitive display, wherein the keyboard includes a plurality of different symbols displayed on respective individual keys; detect a touch input at the touch-sensitive display while the touch-sensitive display is operated in a keyboard mode; in response to detecting the touch input at the touch-sensitive display, determine whether the touch input corresponds to typing at the displayed keyboard; upon determining that the touch input corresponds to typing: interpret the touch input as a keyboard event; and activate one or more keys on the keyboard on the touch-sensitive display based on a location of the touch input; detect, via the touch-sensitive display, a predefined mode-changing gesture over the displayed keyboard; and in response to detecting the predefined mode-changing gesture: cease to display the keyboard on the touch-sensitive display; and operate the touch-sensitive display in a touchpad mode that interprets gestures at the touch-sensitive display as touchpad inputs.
 22. The non-transitory computer-readable storage medium of claim 21, wherein ceasing to display the keyboard on the touch-sensitive display includes: ceasing to display a plurality of symbols on respective individual keys of the keyboard on the touch-sensitive display, and displaying, on the touch-sensitive display, a representation of a touchpad.
 23. The non-transitory computer-readable storage medium of claim 21, wherein detecting the predefined mode-changing gesture includes detecting a user pressing and holding a predefined number of contacts for a predefined amount of time on the touch-sensitive display.
 24. The non-transitory computer-readable storage medium of claim 21, wherein detecting the predefined mode-changing gesture includes detecting that a user has stopped providing typing inputs at the displayed keyboard for at least a predefined amount of time.
 25. The non-transitory computer-readable storage medium of claim 21, wherein detecting the predefined mode-changing gesture includes detecting, via a vibration sensor of the electronic device, a tap outside of the touch-sensitive display.
 26. The non-transitory computer-readable storage medium of claim 21, wherein activating one or more keys on the keyboard on the touch-sensitive display based on a location of the touch input includes determining relative displacement of the touch input relative to a resting position and determining appropriate one or more keys to activate based on the relative displacement.
 27. The non-transitory computer-readable storage medium of claim 21, wherein the executable instructions, when executed by the one or more processors of the electronic device, further cause the electronic device to, after interpreting an additional touch input on the touch-sensitive display as a first touchpad event while the touch-sensitive display is operating in the touchpad mode, move a cursor on the touch-sensitive display in accordance with the touch input.
 28. The non-transitory computer-readable storage medium of claim 27, wherein the executable instructions, when executed by the one or more processors of the electronic device, further cause the electronic device to, after interpreting the additional touch input as the first touchpad event, detect a tap on the touch-sensitive display immediately followed by a dragging motion across the touch-sensitive display and, in response, interpret the sliding motion as a second touchpad event, wherein the second touchpad event corresponds to dragging a currently-displayed object across the touch-sensitive display.
 29. The non-transitory computer-readable storage medium of claim 21, wherein the executable instructions, when executed by the one or more processors of the electronic device, further cause the electronic device to: in response to detecting a sliding motion across the touch-sensitive display while it is operating in the touchpad mode, interpret the sliding motion as a touchpad event, where the sliding motion is distinct from the predefined mode-changing gesture.
 30. The non-transitory computer-readable storage medium of claim 29, wherein the executable instructions, when executed by the one or more processors of the electronic device, further cause the electronic device to, after interpreting the sliding motion as a touchpad event, determine whether a path followed by the sliding motion on the touch-sensitive display traces out a word and, in accordance with a determination that the path followed by the sliding motion traces out the word, output text on the touch-sensitive display corresponding to the word. 